Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). II. Discovery of 32 quasars and luminous galaxies at 5.7 < z ≤ 6.8

Yoshiki Matsuoka, Masafusa Onoue, Nobunari Kashikawa, Kazushi Iwasawa, Michael A. Strauss, Tohru Nagao, Masatoshi Imanishi, Chien Hsiu Lee, Masayuki Akiyama, Naoko Asami, James Bosch, Sébastien Foucaud, Hisanori Furusawa, Tomotsugu Goto, James E. Gunn, Yuichi Harikane, Hiroyuki Ikeda, Takuma Izumi, Toshihiro Kawaguchi, Satoshi KikutaKotaro Kohno, Yutaka Komiyama, Robert H. Lupton, Takeo Minezaki, Satoshi Miyazaki, Tomoki Morokuma, Hitoshi Murayama, Mana Niida, Atsushi J. Nishizawa, Masamune Oguri, Yoshiaki Ono, Masami Ouchi, Paul A. Price, Hiroaki Sameshima, Andreas Schulze, Hikari Shirakata, John D. Silverman, Naoshi Sugiyama, Philip J. Tait, Masahiro Takada, Tadafumi Takata, Masayuki Tanaka, Ji Jia Tang, Yoshiki Toba, Yousuke Utsumi, Shiang Yu Wang

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Abstract

We present spectroscopic identification of 32 new quasars and luminous galaxies discovered at 5.7 < z ≤ 6.8. This is the second in a series of papers presenting the results of the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which exploits the deep multi-band imaging data produced by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. The photometric candidates were selected by a Bayesian probabilistic algorithm, and then observed with spectrographs on the Gran Telescopio Canarias and the Subaru Telescope. Combined with the sample presented in the previous paper of this series, we have now identified 64 HSC sources over about 430 deg2, which include 33 high-z quasars, 14 high-z luminous galaxies, two [OIII] emitters at z ∼ 0.8, and 15 Galactic brown dwarfs. The new quasars have considerably lower luminosity (M1450 ∼ -25 to -22 mag) than most of the previously known high-z quasars. Several of these quasars have luminous (>1043 erg s-1) and narrow (< 500kms-1) Lyα lines, and also a possible mini broad-absorption-line system of N V λ1240 in the composite spectrum, which clearly separate them from typical quasars. On the other hand, the high-z galaxies have extremely high luminosities (M1450 ∼ -24 to -22 mag) compared to other galaxies found at similar redshifts. With the discovery of these new classes of objects, we are opening up new parameter spaces in the high-z Universe. Further survey observations and follow-up studies of the identified objects, including the construction of the quasar luminosity function at z ∼ 6, are ongoing.

Original languageEnglish (US)
Article numberS35
JournalPublications of the Astronomical Society of Japan
Volume70
Issue numberSpecial Issue 1
DOIs
StatePublished - Jan 1 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Active-galaxies
  • Dark ages
  • First stars-galaxies
  • General-quasars
  • High-redshift-quasars
  • Reionization
  • Supermassive black holes

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    Matsuoka, Y., Onoue, M., Kashikawa, N., Iwasawa, K., Strauss, M. A., Nagao, T., Imanishi, M., Lee, C. H., Akiyama, M., Asami, N., Bosch, J., Foucaud, S., Furusawa, H., Goto, T., Gunn, J. E., Harikane, Y., Ikeda, H., Izumi, T., Kawaguchi, T., ... Wang, S. Y. (2018). Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). II. Discovery of 32 quasars and luminous galaxies at 5.7 < z ≤ 6.8. Publications of the Astronomical Society of Japan, 70(Special Issue 1), [S35]. https://doi.org/10.1093/pasj/psx046